Approach control apparatus for railway signaling systems



Oct. 24. 1939 H. G BLQSSER 2,177,089

APPROACH CONTROL APPARATUS FOR RAILWAY SIGNALING SYSTEMS Filed Aug. 12, 1938 I V F 5 18 14 I l I T12 Ea? I; I "In-WW I F' L 'I AP 2 i 15 A R 9 i I I- I LJP a? 15 i "JIM- T 20 B Ham INVENTOR Herman filossen BY HIS ATTORNEY characters designate corresponding parts.

Patented Oct. 24, 1939 I PATENT OFFICE APPROACH CONTROL APPARATUS FOR RAILWAY SIGNALING SYSTEMS Herman G. Blosser, Pittsburgh, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application August 12, 1938, Serial No. 224,564

8 Claims.

My invention relates to approach control apparatus for use in railway signaling systems of the coded track circuit class and it has special reference to the employment of such apparatus for approach controlling various signaling functions without'the use of line wires.

Generally stated, the object of my invention is to improve certain features of an approach control without line wire scheme wherein the rails of each unoccupied signal block length ofxtrack transmit code step pulses of auxiliary energy forwardly from the block entrance to effect the energization of a slow release approach relay at the block exit. I

A more specific object is to supply the referred to pulses of auxiliary energy to themtranceend of each track circuit in a simplified manner which avoids interference with the normal code following operation of the signaling system track relay at that location. 7

In practicing my invention I attain the'above' and other objects and advantages by supplying the auxiliary energy from a low voltage battery which is interposed between the rails and the signaling system track relay connected thereto;

bypolingthis battery in opposition to the higher voltage track battery which supplies the exit end of the signaling system track circuit with the usual coded energy by which the track relay is operated; and by rendering that relay unresponsite to energy from this auxiliary battery.

I shall describe two forms of approach control apparatus embodying my invention, and shall then point out the novel features thereof in claims." I These illustrative embodiments are disclosed in the accompanying drawing in which:

Fig. 1 is a diagrammatic representation of a' single section of railway track which is equipped with my improved approach control apparatus; and

Fig. 2'isa partial representation of a modified form of exit end facilities which are usable with the approacn control scheme of Fig. 1.

In the two views of the drawing, like reference Referring first to Fig. l, the improved approach control apparatus of my invention is there disclosed inassociation with a coded track circuit system of automatic block signalling for a rail- -Way track. l 2 over which it will be assumed g lated-rail joints 3 and the rails. of. each section 1 form a part of a track circuit to which coded signal-control energy is supplied in customary manner.

In this view of Fig. 1, reference characters D and E'respectively designate the entrance and 5 the exit ends of one of these track sections which is illustratively shown as being a full signal block in length; character TR designates a code following track relay which is installed at the entrance end of the section and operated by energy received from the rails thereof; character TB a track battery or other direct current source provided at the section exit for the purpose of supplying theserails with the relay operating energy just referred to; character OR a coding de- 5 vice having a contact 5 which codes this energy by periodically interrupting the rail supply circuit; and character S the usual wayside signal which guards the entrance of each of the track blocks and which is'controlled by the associated track relay TR through the medium of decoding apparatus l0.

An automatic block signalling system of the referred to coded track circuit type operates without the aid of line wiresand in representative form it includes all of the elements above named. Such a-system further comprises the customary facilities (not shown) for continuously operating each of the exit end relays CR at one or another of the usual plurality of distinctive code rates. Selection among these rates (which in a typical three indication system may consist of 80 and 180 energy pulses per minute) is made in accordance with advance traffic conditions by the decoding apparatus Iiifunctioning in customary manner.

This decoding apparatus (details not shown) is controlled in the usual fashion by the associated track relay TR and it performs the further function of selectively setting up a lighting circuit for one or another of the lamps (G, Y and R in the typical three indication system above referred to) of the wayside signal at the same location. In the arrangement represented, these signal lamps derive energizing current from a power source which is designated by the terminals plus and minus. I

In order that certain functions of the signaling system may be rendered active only upon the approach of a train, the apparatus installed at each of the signal locations D, E, etc., is supplemented by an approach relay AR which is arranged to maintain the referred to functions inactive at all times except when the section of track to vthe rear er the location becomes occupied. In the illustrativearrangement which is period of the signal control code (which the con shown at location E in Fig. 1, only one such function is approach controlled and this consists in lighting the wayside signal Sc.

For governing the approach lighting function above stated, the approach relay AR is provided with a contact 9 over the back point of which the signallighting circuits are carried. As will become apparent as the description proceedsthis or companion contacts of the relay AR also may be utilized to approach control signaling functions other than or in addition to the one justnamed. Typically, one such further function may consist in supplying the rails t the, track section tothe rear of the approach lighted signal with coded alternating current energy which is suitable for the control of train carried cab signals (not shown).

When applied to coded signaling systems. of; the conventional character just considered, the improved approach control apparatus herein disele e reader t e. relay A3 a each signa Inca:v tieh epeh i tet e n teeeh r atremand. does this, moreoverQwithout the use of control in Wires the erm h wn i r a sqei tion wi h Signal o k .E. e1 ilie- 1. s. pparatus om r eh renee end eeil t eswhiensun- 1 h e a s t a leek ith nul eso auxilia y. ner y w ic a n t p. t reeurr n periocls Of t e m s nal ntro od an (2.). e a-tend a t e i h e eive the e auxiliary; pulses. from h rails ner ze t e approach, elay. AR in tepwith them,

s e r te at qeatioh Duhy, imnr ved ena e n i eemals use o a. rect. ur ent eree Qt auxiliary ener y. wh eh represented s a battery B, h s att ry a a el a e w c is. su ta ia y ewer than, hat of, the re battery B. atf he se tieh-r'exf and itis eehheeted een herailse ree seetieh Deed d e W d of he ighal nssysteml raels eay T h eceives eratin en rgy. ther from.

This connection; is a serial one and it so de t the p tent al. bat er 212995935- t of h her. v lta e rack. battery.

he er e tte een e ted he rail As a, resu t, the. u rent.

by coding contact 5, i h this lia y. ba t r Alia r h:

letes. through he Win in reels. ela his.

n ct o p o te e hetei. here ay openetins current from. atter -"15.. For. n erehting.

flowing current from battery AB,

In he o w t oeeti nlfl a iia. h cooperating exit end facilitiesincludenreans for connecting thewinding of the approach reiay,AR in energy receiving relation with the rails I, and

2 of the track section D-E during each ofif tinuously operating device CR produces) and means for making this relay AR sufiiciently slow releasing to bridge the intervalsb etween successive connections thereof with the track rails.

The first named means consists in carrying the relay winding circuit over the back point of the coding contact 5 the second named or delay producing means may, of course, take any suit able form, such as a snubbing impedance (not shown) bridged across the winding terminals or internal design expedients (again not shown) incorporated in the relay.

.In operation of the. complete approach con-.

.trolsysi'empf Fig. 1, the track railsv I. and 2. of

section D--E act in the usual maner to transmit energy from one end of the section to the other as long as the section remains unoccupied. Each time, under such conditions, that contact 5 of the coding device CR is in the uppermost or on code period position, the track battery TB picks up the track relay TR over a circuit which may be traced from the positive terminal of the battery through a current limiting impedance l3, conductor I4, track rail I, conductor [5, the opposition connected low voltage battery AB, conductor I6, the winding of relay TR, conductor I1, track rail 2, conductor l8 and front contact 5 of device CR back to the negative terminal of battery TB.

As previously stated, the potential of the auxiliary battery AB is substantially less than that or the, signaling system track battery TB. For example, while battery AB may consist of a single primary cell, battery TB preferably will be made up of two, three or even four of such cells, thereby not only completely overcoming the, opposing voltage of battery AB but providing at all times sufiicient excess normal polarity potential to pick up the track relay TR. each time that the coding contact 5 is in the uppermost or on. period position.

Each time that this contact occupies, the lowermost or off code period position, the trackrelay TR releases. Again this release takesplace in normal manner and is undelayed bythe reverse AB supplies the track railsduring the off pe riods, As already mentioned, relay TR preferably is a device having polarized response characteristics and in that" event it is adapted tq pick; up y when he e ehhih lther e v smade positive with respect to the rightterminal, With the particular connections which are, shown in Fig. 1, this happenseach time that coding contact 5 connects the track batteryTB with the rails and makes rail I positive withrespect. to rail 2. Considering the auxiliary-battery AB, it will be seen that while it also tends to make rail l positive with respect to rail 2, it can ci-re. culate current through the winding oi relay, TR: only in the reverse direction. The effect of such; reverse current is not to pick up therelay, con; tactsbut rather to urge them more positivelyinto their fullyjreleased positions.

Each "ofi period or lowermost position of the codingcontact 5 connects the winding or the slow release approach relay AR in energy receiving relation with the track rails}! and 2 and thus impresses upon it the voltage at which the au g; iliary battery AB maintains these rails during the off periods of the signalcontrol code. During each of such periods this battery ABsup plies relay AR with a pulse of energizing current over;

a circuit which may be traced from the positive terminal of the battery through conductor 15, track rail I, conductor M, the winding of relay AR, conductor 25, back contact 5 of device CB conductor [8, track rail 2, conductor, H, the

winding of relay TR and conductor ldbac stos g thenegative terminal of battery AB.

As long as the track section DE remains va,-.

cant, therefore, the operating winding ofthe. ap: proach relay AB. is energized in step. with each, off period of the signal control code over the circuit just traced. Because of its slow releas-. ing characteristics the relay now holds its CO1): tact 9 continuously picked up and thereby maintains the lighting circuits of the wayside signal Sedisconnectedirom their energizing source In.

flowing current with which the auxiliary battery 7 this manner the approach controlled signaling function just named is continued inactive as long as the track section remains vacant.

In the event, now, that a train comes into the section D-E, the usual shunting action of its wheels and axles cuts off the transmission over the rails l and 2 of energy from battery TB to relay TR and also of energy from the auxiliary battery AB at the section entrance to the approach relay AR at the section exit. Now continuously deenergized, this approach relay releases and contact 9 thereof completes the energizing circuit for the signal See. In consequence, that signal lights the particular lamp selected by the decoding equipment l0.

As soon as the rear of the departing train clears location 6, the track circuit again transmits coded direct current energy to the track relay TR at location D, auxiliary battery AB again supplies the track rails with low potential energy during the off periods of the signal control code, these rails transmit this auxiliary energy forwardly to location E and the there located approach relay AR receives the recurring pulses of this energy over coding contact 5 of device CR. In again picking up in response to these pulses, contact 9 of relay AR restores the associated wayside signal Se to its normally inactive state.

Referring now to Fig. 2, I have there represented a somewhat modified form of exit end facilities which may be used in place of the apparatus represented at E in Fig. 1. These are generally equivalent to the corresponding facilities earlier described and in considering them it will be helpful 'toassume that the conductors i4 and I8 of Fig. 2 are joined at location E with the track railsl and 2 of Fig. 1 which extend rearwardly to location D of the same figure where they are connected with track relay TR and auxiliary battery AB.

The modified facilities of Fig. 2 differ, however, from those in Fig. 1 in that a sensitive code following detector relay KR is interposed between the track rails and the slow release approach relay AR in a manner similar to that disclosed and claimed by each of the following copending applications: Serial No. 218,923, filed July 3, 1938, by Charles B. Shields; Serial No. 220,015, filed July 19,1938, by Crawford EV Staples; Serial No. 221,317, filed July 26, 1938, by Edward U. Thomas; Serial No. 222,014, filed July 29, 1938, by Herman G.,Blosser; and Serial No. 223,076, filed August 4, 1938, by Herman G. Blosser. This added relay KR performs two functions. First, it increases the sensitivity of the exit end apparatus and thereby enables the approach relay to respond to comparatively weak pulses of auxiliary energy which may be received from the track circuit. Second, it insures that the approach relay AR cannot be continuously energized from the auxiliary battery AB in the event that the coding contact 5 is stopped in the lowermost or o code period position.

From a comparison of the diagrams of Figs. 1 and 2 it will be seen that the winding of detector relay KR of Fig. 2 is connected by coding contact and for the duration of each of the pulses of auxiliary energy which the winding of the relay receives from the auxiliary battery AB at the entrance end of the section. Between pulses, of course, relay KR releases in the usual code following manner.

Controlled by this contact 22 of relay KR is an energizing circuit for the winding of the associated approach relay AR which circuit is shown as being identified with local power supply terminals plus and minus and which includes a transformer AT. With the arrangement of devices KR, AT and AR that is shown in Fig. 2 (which arrangement embodies principles that are disclosed and claimed in a copending application Serial No. 210,744, filed May 28, 1939, by Frank H. Nicholson et al.) the recurring auxiliary energy pulses from the battery AB act through relay KR to cause the local source just referred to to supply similarly timed pulses of energizing current to the relay AR.

As in the case of Fig. 1, this approach relay AR is provided with a contact 9 which controls the energizing circuit for the associated wayside signal S (not shown in Fig. 2). As in the case of Fig. 1 also, the relay AR has slow releasing characteristics imparted thereto by any suitable means, such as the use of a snubbing element (again not shown) or internal design expedients.

In operation of the exit end facilities of Fig. 2, each time, under vacant conditions of the track section (see D-E of Fig. 1), that contact 5 of the coding device CR is in the uppermost or on period position, the track battery TB supplies the rails with energy for picking up the track relay TR (see location D of Fig. 1) in the same manner as in Fig. 1. Each time, likewise, that the coding contact 5 occupies the lowermost or off period position, the winding of relay KR is connected in energy receiving relation with the rails and has impressed thereon a pulse of auxiliary energy from battery AB (again see location D of Fig. 1). As will be evident from the diagram, this energy supply isover conductors I4 and I8 and back contact 5.

In receiving these recurring pulses of auxiliary energy, the detector relay KR at the sectionv exit responds to them in code following manner. In so responding that relay causes contact 22 thereof to pole change the primary circuit of the transformer AT which is interposed between the approach relay AR and the local direct current source with which the terminals plus and minus are identified. From this transformer output energy of code pulse frequency is supplied to the operating winding of relay AR over circuits which include a rectifying contact 23 of the detector relay.

As long as this recurrent energization of the slow release approach relay AR continues, that relay holds its contact 9 picked up and in this manner the wayside signal Se (see Fig. 1) is maintained inactive until a train comes into the associated section of track.

When that happens, the usual shunting action of the train wheels and axles cuts off the transmission through the rails l and 2 of the auxiliary energy to the detector relay KR and in consequence that relay releases continuously. This causes the approach relay AR to become deenergized due to the inability of the transformer AT to generate secondary voltage when its primary circuit is subjected to unvarying direct current. Contact!) of relay AR accordingly releases and thereby lights the associated wayside signal in desired manner.

As soon as the rear of the departing train clears the exit end of the associated tracksection the rails of that section again transmit off period pulses of auxiliary energy from the entrance end battery AB forwardly to the exit end detector relay KR. In once more responding, that code following device operates contacts 22 and 23 in the primary and secondary circuits of transformer AT and thereby causes the associated slow release'approach relay AR again to be energized. The approach relay once more picks up and in so doing restores the associated wayside signal to its normally inactive condition.

From the foregoing it will be seen that I have provided simplified and otherwise improved en-' trance end facilities for an approach control without line wire scheme wherein use is made of forwardly fed pulses of auxiliary energy which are supplied to the track circuit during the off periods of the main signal control code. As these facilities are entirely a function of the track circuit and apparatus which is directly associated therewith, they are independent of the coding and decoding apparatus of the coded signaling system with which they are combined and hence they are usable with signaling systems which employ a wide variety of different types and forms of such apparatus. Moreover, while I have explained my invention in an application wherein the lights of the wayside signal only are approach controlled, it will be understood that other comparable functions may also be provided for A instead of or in addition to the illustrative one just named.

Although I have herein shown and described only two forms of approach control apparatus embodying my invention, it will be understood that various changes and modifications may be- 4& Having thus described my invention, what I claim is:

1. In combination with a section of railway track, a source of signal control energy at the exit end of said section, similarly located means for recurrently connecting said source with the 1 opposite polarity current, a circuit so connecting the winding of said track relay across said rails that the said coded signal control energy which is received from those rails passes given polarity current through said winding and thereby operates the relay, a source of auxiliary energy having a voltage which is substantially less than that of said exit end signal control source and being serially included in said track relay winding circuit in polarity opposing relation to the energy of said received signal control code whereby to supply a pulse of auxiliary energy to said rails during each ofi period of that received code and to do this without falsely operating the track relay, a slow release approach relay located at the section exit and energized in step with the said recurring pulses of auxiliary energy which are there received from said rails whereby to be maintained continuously picked up as long, as said section is vacant and to release only when a train comes into the section, and traific governingi apparatus controlled by said approach relay, V g

2. In combination with a section of railway track, a source of direct current signal control energy at the exit end ofsaid section, similarly located/means for recurrently connecting said source with the section rails whereby to produce a signal control code consisting of alternate on and off periods, a code following track relay which is responsive to given polarity current but not to opposite polarity current, a circuit connecting the winding of said relay across said rails in such manner that the said coded signal control energy which is received from those rails passes given polarity current through said winding and thereby operates the relay, an auxiliary source of direct current energy having a voltage which is-substantially less than that of said signal control, source and being serially included in said track relay circuitin polarity opposing relation to the energy ofsaid received signal control code whereby without falsely operating the track relay to supply a pulse of auxiliary energy to said rails during each of the said off periods of that received code, a slow release approach relay at said section exit, similarly located means controlled by said recurring pulses of auxiliary energy which are received from said rails for energizing said approach relay in step with those received pulses whereby to maintain the approach relay continuously picked up as long as said section is vacant and to allow that relay to release only when a train comes into the section, and traflic governing apparatus controlled by said approac relay. 7

3. In combination with a section of railway track, a source of direct current signal control energy at the exit end of said section, a similarly located coding device which recurrently connects said source with the section rails and thereby produces a signal control code consisting of ing track relay which can be picked up by givenv polarity energy but not by opposite polarity energy, a circuit connecting the operating winding of said track relay across said rails in such manner that the said coded energy which the'winding receives from those rails has said given polarity and picks up the relay during each on period of the received signal control code, an auxiliary source of direct current energy having a voltage substantially lower than that of said signal control source and being serially included in said track relay circuit in a manner to oppose the said signal control energy which the winding of said track relay receives from said rails whereby without falsely picking up the track relay to supply a pulse of auxiliary energy to those rails during each off period of the received signal control code, a slow release approach relay located at the section exit and energized in step with the said recurring pulses of auxiliary energy which are there received from said rails whereby to bemaintained continuously picked up as long as said section is vacant and to release only when exit end of said section, a similarly located approach governing relay, a coding device having a contact which repeatedly connects the rails of said section first to said energy source and then to the winding of said relay and thereby pro-i duces a signal control code consisting of alternate on and ofi periods the latter of which coincide with said relay winding connections, a code following track relay connected in energy receiving relation with said rails and being arranged to respond to the said coded signal control energy which is received therefrom but not to energy which is of opposite polarity, a source of auxiliary energy having a voltage which is substantially less than that of said signal control source and being serially included in said track relay connection in polarity opposing relation to the signal control source whereby under vacant conditions of said section to excite said approach governing relay over said rails during each off period of the said signal control code, and trafiic governing apparatus controlled by said approach governing relay and rendered active when the said recurring excitation for that relay is cut off by the presence of a train in said section.

5. In combination with a section of railway track, a source of direct current signal control energy at the exit end of said section, a similarly located coding device which recurrently connects said source with the section rails and thereby produces a signal control code consisting of alternate on and off periods of given polarity energy, an approach governing relay also at the section exit, means controlled by said coding device for connecting said relay in energy receiving relation with said rails during each of the said off code periods, a code following track relay connected with said rails at all times and being arranged to respond to the said coded given polarity energy which i received therefrom but not to energy which is of the opposite polarity, an auxiliary source of direct current energy serially included in said track relay connection in polarity opposing relation to said signal control source whereby under vacant conditions of said section to excite said approach governing relay over said rails during each off period of the said received signal control code, and trafiic governing apparatus controlled by said approach governing relay and rendered active when that relay becomes continuously deenergized in response to the presence of a train in said section.

6. In combination: a section of railway track, a source of direct current signal control energy at the section exit, means for recurrently connecting said source with the section rails whereby to produce a signal control code consisting of alternate on and off periods, a code follow ing track relay which is responsive to" given polarity energy but not to opposite polaritye fiergy, an auxiliary source of direct current energy having a voltage which is substantially less than that of said signal control source, a circuit serially connecting the operating winding of said track relay and said auxiliary source across said section rails in such manner that each on periodpulse of the said coded signal control energy which is received from those rails by said winding has said given polarity and picks up the track relay while the energy which said auxiliary source supplies to said rails during the off periods of the received code passes through the relay winding in the opposite polarity direction and does not operate the track relay, an approach governing relay at said section exit which is excited by the off code period pulses of said auxiliary energy that are there received under vacant conditions of said section, and traffic governing apparatus controlled by said approach governing relay and rendered active when that relay becomes continuously deenergized in response to the presence of a train in said section.

7. In combination with a section of railway track, a source of signal control energy at the section exit, a similarly located approach relay which has slow release characteristics, a coding device which repeatedly connects the rails of said section first to said energy source and then to the winding of said approach relay and thereby produces a signal control code consisting of alternate on and off periods the latter of which coincide with said relay winding connections, a code following track relay connected with said rails at the section entrance and arranged to respond to the said coded signal control energy which is there received from those rails but not to energy which is of opposite polarity, a similarly located source of auxiliary energy having a voltage which is substantially less than that of said signal control source and being serially included in said track relay connection in polarity opposing relation to the signal control source whereby to excite said slow release approach relay over said rails during each off period of the said received signal control code and thereby maintain that relay continuously picked up as long as said section is vacant, and traiiic governing apparatus controlled by said approach relay and rendered active when that relay releases in response to the presence of a train in said section.

8. In combination with a section of railway track, a source of signal control energy at the section exit, a similarly located code following detector relay, a coding device which repeatedly connects the rails of said section first to said energy source and then to the winding of said detector relay and thereby produces a signal control code consisting of alternate on and off periods the latter of which coincide with said relay winding connections, a code following track relay connected with said rails at the section entrance and arranged to respond to the said coded signal control energy which is there received from those rails but not to energy that is of opposite polarity, a similarly located source of auxiliary energy having a voltage which is substantially less than that of said signal control source and being serially included in said track relay connection in polarity opposing relation to the said signal control source whereby to excite said exit and detector relay over said rails during each off period of the said received signal control code and thereby cause that relay recurrently to pick up under vacant conditions of said section, a slow release approach relay energized instep with the said recurrent pick-ups of the detector relay whereby to be maintained continuously picked up as long as said section remains vacant and to release only when a train comes into the section, and trafiic governing apparatus controlled by said approach relay.

HERMAN G. BLOSSER. 

